1. Field of the Invention
The present invention relates to improved hydraulic cement adhesive compositions which are particularly adapted to be admixed with water or aqueous media and used wherever thin set mortars or tile adhesives are required. Such uses include, for example, installing ceramic tile, brick, ceramic mosaics, marble, quarry tile, slate, pavers or stone over surfaces including concrete, masontry, brick, gypsum wall board, gypsum plaster, or stone.
When admixed with latex compositions, the hydraulic cement adhesive compositions of the invention can advantageously be utilized on surfaces such as asbestos, cement board, plywood, wood surfaces and flakeboard.
2. Description of the Prior Art
Conventional cement adhesives or mortars, contain hydraulic cement, generally Portland or calcium aluminite cement, sand and fillers, such as limestone.
While such conventional mortars provide bonding properties, non-flammability characteristics and resistance to attack by insects, fungi or rodents, they are deficient in certain applications. In particular, relatively thick layers are required for tile-setting purposes and such layers not only involve substantial labor in mixing and application, but also lack the desired high-bonding strength and a resistance against the effects of shock, frost and moisture.
In order to provide hydraulic cement compositions which could be applied in thin layers, particularly for use in vertical applications such as tile on walls, it has been known in the prior art to incorporate finely divided inorganic fibers, for example mineral wool, glass wool, asbestos or the like, in hydraulic cement-based mortars. This improved the thixopropic properties of the mortar and thereby improved somewhat the sagging and poor adhesion of these mortars in thin layer applications. However, incorporation of such fibers involves increased expense and, particularly in the case of asbestos, poses a potential health problem to those making or applying the materials. Fiber glass is an irritant to the skin and can cause dermatitis to workmen continuously exposed to it.
Furthermore, cellulose and alkyl derivatives of cellulose, for example methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and the like, have been incorporated into hydraulic cement compositions to improve its adaptability to thin layer applications. For example, U.S. Pat. Nos. 2,820,717; 2,934,932; 3,243,307 and 3,824,101 all disclose incorporation of one or more alkyl cellulose materials in hydraulic cement mortar compositions of the general type upon which the present invention is an improvement.
However, even with the addition of cellulose and alkyl cellulose materials, conventional mortar compositions lack the desired high-bonding strength, superior resistance to chemicals, shock and frost, and permanent water-proof bonding which is desired, particularly in thin layer applications.